Generation of harq-ack information and power control of harq-ack signals in tdd systems with downlink of carrier aggregation

ABSTRACT

Methods and apparatus are provided for a User Equipment (UE) configured to have multiple cells in a DownLink (DL) of a Time Division Duplex (TDD) communication system so as to determine a power of an acknowledgement signal that the UE transmits in a control channel and to determine a number of acknowledgement information bits that the UE multiplexes with data information bits in a data channel. A transmission power of the control signal is determined based on DL Assignment Index (DAI) Information Elements (IEs) in DL Scheduling Assignments (SAs) that the UE detects through multiple transmission time intervals and through the multiple configured DL cells. The number of acknowledgement information bits in the data channel is determined based on a DAI IE of an UpLink (UL) SA associated with the transmission of the data channel.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of prior application Ser. No.13/958,908 filed Aug. 5, 2013, which claims the benefit of U.S. patentapplication Ser. No. 13/288,317 filed Nov. 3, 2011 in the U.S. Patentand Trademark Office, which claims benefit under 35 U.S.C. §119(e) ofU.S. Provisional Application No. 61/409,662, filed on Nov. 3, 2010, inthe United States Patent and Trademark Office, the disclosure of whichis incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally directed to a wireless communicationsystems and, more specifically, to the transmission of acknowledgementinformation in an uplink of a communication system.

2. Description of the Art

A communication system includes a DownLink (DL) that conveystransmission signals from a Base Station (BS), or NodeB, to UserEquipment (UE) and an UpLink (UL) that transmits signals from UEs to theNodeB. A UE, also commonly referred to as a terminal or a mobilestation, may be fixed or mobile and may be a wireless device, a cellularphone, a personal computer device, a mobile electronic device, or anyother similar fixed or mobile electronic device. A NodeB is generally afixed station and may also be referred to as an access point or someother equivalent terminology.

More specifically, the UL transmits data signals carrying informationcontent, of control signals providing control information associatedwith the transmission of data signals in the DL, and of ReferenceSignals (RSs), which are commonly referred to as pilot signals. The DLalso conveys transmissions of data signals, control signals, and RSs.

UL data signals are transmitted through a Physical Uplink Shared CHannel(PUSCH) and DL data signals are conveyed through a Physical DownlinkShared CHannel (PDSCH). In a case where a PUSCH transmission does notoccur, a UE conveys UL Control Information (UCI) through a PhysicalUplink Control CHannel (PUCCH). However, when a PUSCH transmissionoccurs, a UE may convey UCI together with data through the PUSCH.

DL control signals may be broadcast or sent in a manner that isUE-specific. Accordingly, UE-specific control channels can be used,among other purposes, to provide UEs with Scheduling Assignments (SAs)for PDSCH reception, or in other words, a DL SA, or a PUSCHtransmission, or in other words, a UL SA. The SAs are transmitted fromthe NodeB to respective UEs using DL Control Information (DCI) formatsthrough respective Physical DL Control CHannels (PDCCHs).

The NodeB may configure a UE through higher layer signaling, such asRadio Resource Control (RRC) signaling, a PDSCH and a PUSCH TransmissionMode (TM). The PDSCH TM or PUSCH TM is respectively associated with a DLSA or a UL SA and defines whether the respective PDSCH or PUSCH conveysone data Transport Block (TB) or two data TBs.

PDSCH or PUSCH transmissions are either scheduled to be assigned to a UEby the NodeB through higher layer signaling or through physical layersignaling, such as PDCCH signaling, using a respective DL SA or UL SA,or correspond to non-adaptive retransmissions for a given HybridAutomatic Repeat reQuest (HARQ) process. Scheduling by higher layersignaling is referred to as Semi-Persistent Scheduling (SPS), andscheduling by PDCCH is referred to as dynamic scheduling. A PDCCH mayalso be used to release a SPS PDSCH or a SPS PDSCH. If a UE misses aPDCCH, or in other words, fails to detect a PDCCH, it also misses theassociated PDSCH or PUSCH. This event will be referred to as aDiscontinuous Transmission (DTX).

The UCI includes ACKnowledgment (ACK) information associated with a HARQprocess, i.e., a HARQ-ACK. The HARQ-ACK information may consist ofmultiple bits corresponding to positive ACKs for TBs the UE correctlyreceived or negative acknowledgements (NACKs) for TBs the UE incorrectlyreceived. In a case where a UE does not receive a TB, it may transmit aDTX, which includes tri-state HARQ-ACK information, or both the absenceand the incorrect reception of a TB can be represented by a NACK (in acombined NACK/DTX state). One consequence of a UE not conveying a DTX tothe NodeB is that Incremental Redundancy (IR) cannot be used for itsHARQ process. This leads to throughput loss. Another consequence is thatPDCCH power control, based on DTX feedback, is not possible.

In Time Division Duplex (TDD) systems, DL and UL transmissions occur indifferent Transmission Time Intervals (TTIs) which are referred to assubframes. For example, in a frame comprising of 10 subframes, somesubframes may be used for DL transmissions and some may be used for ULtransmissions.

FIG. 1 illustrates a frame structure for a TDD system according to therelated art.

Referring to FIG. 1, a 10 millisecond (ms) frame consists of twoidentical 5 ms half-frames. Each 5 ms half-frame 110 is divided into 8slots 120 and 3 special fields: a DL Pilot Time Slot (DwPTS) 130, aGuard Period (GP) 140, and an UL Pilot Time Slot (UpPTS) 150. The lengthof DwPTS+GP+UpPTS is one subframe 160 and is 1 ms long. The DwPTS may beused for the transmission of synchronization signals from the NodeBwhile the UpPTS may be used for the transmission of random accesssignals from UEs. The GP facilitates the transition between DL and ULtransmissions by absorbing transient interference.

The number of DL subframes and the number of UL subframes per frame canbe different from each other and multiple DL subframes may be associatedwith a single UL subframe. The association between the multiple DLsubframes and the single UL subframe is in the sense that HARQ-ACKinformation of bits generated in response to PDSCH receptions (which aredata TBs) in the multiple DL subframes needs to be transmitted in thesingle UL subframe. This number of DL subframes is referred to as thebundling window and, in the example of FIG. 1, it is usually smallerthan or equal to 4 subframes and it is always smaller than or equal to 9subframes.

One method for a UE to convey HARQ-ACK information in a single ULsubframe, in response to receiving PDSCHs in multiple DL subframes, isHARQ-ACK bundling where the UE transmits an ACK only if it correctlyreceives all data TBs, otherwise, the UE transmits a NACK. Therefore,HARQ-ACK bundling results in unnecessary retransmissions and reduced DLthroughput as a NACK is transmitted even when a UE incorrectly receivesonly one data TB and correctly receives all other data TBs.

Another method for a UE to convey HARQ-ACK information in a single ULsubframe, in response to receiving data TBs in multiple DL subframes, isHARQ-ACK multiplexing, which is based on PUCCH resource selection.

Yet another method for a UE to convey HARQ-ACK information in a singleUL subframe, in response receiving data TBs in multiple DL subframes, isjoint coding of the HARQ-ACK bits using, for example, a block code suchas the Reed-Mueller (RM) code, which will be described below. Theprimary focus of the descriptions herein is on joint coding of HARQ-ACKbits. Although the transmission of HARQ-ACK information was describedfor brevity only for a PUCCH, the coding method is fundamentally thesame for transmission in a PUSCH.

If a PDSCH conveys one TB, the respective HARQ-ACK information consistsof one bit which is encoded as a binary ‘1’ if the TB is correctlyreceived, such that the binary ‘1’ indicates an ACK, and is encoded as abinary ‘0’ if the TB is incorrectly received, such that the binary ‘0’indicates a NACK. If a PDSCH conveys two TBs, in accordance with theSingle User-Multiple Input Multiple Output (SU-MIMO) transmission methodwith a rank higher than one, the HARQ-ACK information consists of twobits [o₀ ^(ACK) o₁ ^(ACK)] with o₀ ^(ACK) corresponding to the first TBand o₁ ^(ACK) corresponding to the second TB. If a UE applies bundlingin the spatial domain, it generates only one HARQ-ACK bit. Thetransmission of one HARQ-ACK bit may use repetition coding and thetransmission of two HARQ-ACK bits may use a (3, 2) simplex code.

FIG. 2 illustrates a PUSCH transmission structure according to therelated art.

Referring to FIG. 2, the subframe 210 includes two slots. Each slot 220includes N_(symb) ^(UL) symbols used to transmit data, a HARQ-ACK, or aRS. Each symbol 230 includes a Cyclic Prefix (CP) to mitigateinterference due to channel propagation effects. The PUSCH transmissionin one slot may be either at a same BandWidth (BW) or at a different BWthan in the other slot. Some symbols in each slot are used to transmitRS 240, which enables channel estimation and coherent demodulation ofthe received data and/or HARQ-ACK information. The transmission BWconsists of frequency resource units which will be referred to asPhysical Resource Blocks (PRBs). Each PRB includes N_(sc) ^(RB)sub-carriers, or Resource Elements (REs), and a UE is allocatedM_(PUSCH) PRBs 250 for a total of M_(sc) ^(PUSCH)=M_(PUSCH)·N_(sc) ^(RB)REs for the PUSCH transmission BW.

The last subframe symbol may be used for transmitting a Sounding RS(SRS) 260 from one or more UEs. The SRS provides the NodeB an estimateof the channel medium the respective UE experiences over the SRStransmission BW. The NodeB configures to each UE the SRS transmissionparameters through higher layer signaling such as RRC signaling. Thenumber of subframe symbols available for data transmission is N_(symb)^(PUSCH)=2·(N_(symb) ^(UL)−1)−N_(SRS), where N_(SRS)=1 if the lastsubframe symbol is used for SRS transmission and N_(SRS)=0 otherwise.

Each RS or SRS is assumed to be constructed using a Constant AmplitudeZero Auto-Correlation (CAZAC) sequence. Orthogonal multiplexing of CAZACsequences can be achieved by applying different Cyclic Shifts (CSs) tothe same CAZAC sequence.

FIG. 3 illustrates a transmitter for transmitting data and HARQ-ACK in aPUSCH according to the related art.

Referring to FIG. 3, encoded HARQ-ACK bits 320 are inserted bypuncturing encoded data bits 310 by the data puncturing unit 330. ADiscrete Fourier Transform (DFT) is then performed by the DFT unit 340.The REs for the PUSCH transmission BW are selected by the sub-carriermapping unit 350 as instructed from a controller 355. An Inverse FastFourier Transform (IFFT) is performed by an IFFT unit 360, CP insertionis performed by a CP insertion unit 370, and time windowing is performedby a filter 380, thereby generating a transmitted signal 390. Forbrevity, the encoding and modulation processes and additionaltransmitter circuitry such as a digital-to-analog converter, analogfilters, amplifiers, and transmitter antennas are not illustrated.

The PUSCH transmission is assumed to be over a single cluster 395A orover multiple clusters 395B of contiguous REs in accordance to the DFTSpread Orthogonal Frequency Division Multiple (DFT-S-OFDM) method forsignal transmission.

FIG. 4 illustrates a receiver for receiving a transmission signal asillustrated in FIG. 3 according to the related art.

Referring to FIG. 4, an antenna receives a Radio-Frequency (RF) analogsignal and after further processing by units such as filters,amplifiers, and analog-to-digital converters, which are not shown forthe purpose of brevity, a received digital signal 410 is filtered by afilter 420 for time windowing and the CP is removed by CP removal unit430. Subsequently, the receiver unit applies a FFT by an FFT unit 440,selects the REs used by the transmitter by sub-carrier de-mapping by asub-carrier demapping unit 450 under a control of controller 455.Thereafter, an Inverse DFT (IDFT) unit 460 performs an IDFT, anextraction unit 470 extracts the HARQ-ACK bits and places erasures atthe respective REs for the data bits, and finally generates the databits 480.

Assuming for simplicity that the PUSCH conveys a single data TB, forHARQ-ACK transmission in a PUSCH a UE determines the respective numberof encoded HARQ-ACK symbols as shown in Equation (1)

$\begin{matrix}{Q^{\prime} = {\min( {\lceil \frac{O_{{HARQ}\text{-}{ACK}} \cdot \beta_{offset}^{{HARQ} - {ACK}}}{Q_{m} \cdot R} \rceil,{4 \cdot M_{sc}^{PUSCH}}} )}} & {{Equation}\mspace{14mu} (1)}\end{matrix}$

In Equation (1), O_(HARQ-ACK) is a number of HARQ-ACK information bits,also referred to as a HARQ-ACK payload, β_(offset) ^(HARQ-ACK) is aparameter that the NodeB conveys to the UE through higher layersignaling, Q_(m) is a number of data information bits per modulationsymbol (Q_(m)=2, 4, 6 for Quadrature Phase Shift Keying (QPSK),Quadrature Amplitude Modulation (QAM) 16, QAM64, respectively), R is adata code rate of an initial PUSCH transmission for the same TB, M_(sc)^(PUSCH) is a PUSCH transmission BW in a current subframe, and ┌ ┐ isthe ceiling function that rounds a number to a next integer.

The data code rate is defined as shown in Equation (2)

$\begin{matrix}{R = {( {\sum\limits_{r = 0}^{{CB} - 1}K_{r}} )/( {Q_{m} \cdot M_{sc}^{{PUSCH}\text{-}{initial}} \cdot N_{symb}^{{PUSCH}\text{-}{initial}}} )}} & {{Equation}\mspace{14mu} (2)}\end{matrix}$

In Equation (2), CB is a total number of data code blocks, K_(r) is anumber of bits for a data code block number r, N_(symb) ^(PUSCH-initial)is a number of subframe symbols for the initial PUSCH transmission ofthe same TB and M_(sc) ^(PUSCH-initial) is a number of respective REsfor the PUSCH transmission BW. The maximum number of encoded HARQ-ACKsymbols is limited to the number of REs in 4 DFT-S-OFDM symbols(4·M_(sc) ^(PUSCH)) which may be located in the two subframe symbolsadjacent to the RS in each of the two subframe slots, as shown in FIG.2. The determination of the number of encoded HARQ-ACK symbols in a casewhere a PUSCH conveys multiple TBs, using for example the SU-MIMOtransmission method, is similar to the case where a PUSCH conveys oneTB, and thus, a respective description is omitted for brevity.

FIG. 5 illustrates a PUCCH structure in one subframe slot for thetransmission of multiple HARQ-ACK information bits using the DFT-S-OFDMtransmission method according to the related art.

Referring to FIG. 5, after encoding and modulation, using respectively,for example, a RM block code and QPSK (not shown for brevity), a set ofthe same HARQ-ACK bits 510 is multiplied by mixer 520 with elements ofan Orthogonal Covering Code (OCC) 530 and is subsequently DFT precodedby the precoder unit 540. For example, for 5 symbols per slot carryingHARQ-ACK bits, the OCC has a length of 5 {OCC(0), OCC(1), OCC(2),OCC(3), OCC(4)} and can be either of {1, 1, 1, 1, 1}, or {1, exp(j2π/5),exp(j4π/5), exp(j6π/5), exp(j8π/5)}, or {1, exp(j4π/5), exp(j8π/5),exp(j2π/5), exp(j6π/5)}, or {1, exp(j6π/5), exp(j2π/5), exp(j8π/5),exp(j4π/5)}, or {1, exp(j8π/5), exp(j6π/5), exp(j4π/5), exp(j2π/5)}. Theoutput of the DFT precoder is passed through an IFFT unit 550 and it isthen mapped to a DFT-S-OFDM symbol 560.

As the previous operations are linear, their relative order may beinter-changed. Because the PUCCH transmission is assumed to be in onePRB which consists of N_(sc) ^(RB)=12 REs, there are 24 encoded HARQ-ACKbits transmitted in each slot (which includes 12 HARQ-ACK QPSK symbols)and a (32, O_(HARQ-ACK))RM code is punctured into a (24, O_(HARQ-ACK))RMcode. The same or different HARQ-ACK bits may be transmitted in thesecond subframe slot. A RS is also transmitted in each slot to enablecoherent demodulation of the HARQ-ACK signals. The RS is constructedfrom a CAZAC sequence 570, having a length of 12, which is passedthrough an IFFT 580 and mapped to another DFT-S-OFDM symbol 590.

The PUCCH structure of FIG. 5 can only support limited HARQ-ACK payloadswithout incurring a large coding rate because it can only support 24encoded HARQ-ACK bits. For example, a single RM code can be used forHARQ-ACK payloads up to 10 bits and a dual RM code can be used forHARQ-ACK payloads between 11 and 20 bits. With a dual RM code, themapping to successive elements of the DFT can alternate between elementsfrom the output of a first RM code and elements from the output of asecond RM code in a sequential manner, which is not shown for brevity.For HARQ-ACK payloads of more than 20 bits, convolutional coding can beused.

FIG. 6 illustrates a UE transmitter block diagram for HARQ-ACK signalsin a PUCCH according to the related art.

Referring to FIG. 6, the HARQ-ACK information bits 605 are encoded andmodulated by an encoder and modulator 610 and then multiplied with anelement of the OCC 625 for the respective DFT-S-OFDM symbol by a mixer620. The output of the mixer 620 is then precoded by a DFT precoder 630.After DFT precoding, sub-carrier mapping is performed by a sub-carriermapper 640, under control of controller 650. Thereafter, the IFFT isperformed by an IFFT unit 660, a CP is added by a CP inserter 670, andthe signal is filtered by a filter 680 for time windowing, therebygenerating a transmitted signal 690. For brevity, additional transmittercircuitry, such as a digital-to-analog converter, analog filters,amplifiers, and transmitter antennas are not illustrated in FIG. 6.

FIG. 7 illustrates a NodeB receiver block diagram for HARQ-ACK signalsaccording to the related art.

Referring to FIG. 7, after receiving a Radio-Frequency (RF) analogsignal and converting it to a digital received signal 710, the digitalreceived signal 710 is filtered by a filter 720 for time windowing and aCP is removed by a CP remover 730. Subsequently, the NodeB receiverapplies a FFT by a FFT unit 740, performs sub-carrier demapping by asub-carrier demapper 750 under the control of a controller 755, andapplies an Inverse DFT (IDFT) by an IDFT unit 760. The output of theIDFT unit 760 is then multiplied with an OCC element 775 for therespective DFT-S-OFDM symbol by a mixer 770. An adder 780 sums theoutputs for the DFT-S-OFDM symbols conveying HARQ-ACK signals over eachslot, and a demodulator and decoder 790 demodulates and decodes thesummed HARQ-ACK signals over both subframe slots in order to obtain theHARQ-ACK information bits 795.

In TDD systems, as a UE needs to transmit HARQ-ACK informationcorresponding to potential TB receptions over multiple DL subframes, aDL Assignment Index (DAI) Information Element (IE), or DL DAI IE,V_(DAI) ^(DL), is included in each DL SA in order to assist the UE indetermining there is a HARQ-ACK payload it should convey in a PUCCH. Asthe NodeB cannot predict whether there will be a DL SA for a given UE infuture DL subframes, the V_(DAI) ^(DL) is a relative counter which isincremented in each DL SA transmitted to a UE and starts from thebeginning after the DL subframe is linked to the UL subframe of theHARQ-ACK signal transmission. Then, if the last DL SA is missed by theUE, the incorrect HARQ-ACK payload is transmitted which may causeincorrect understanding of at least some of the HARQ-ACK bits at theNodeB. In all following descriptions, the DL DAI IE is assumed toconsist of 2 bits with the values of “00”, “01”, “10”, “11” respectivelyindicating V_(DAI) ^(DL)=1, V_(DAI) ^(DL)=2, V_(DAI) ^(DL)=3, andV_(DAI) ^(DL)=4.

FIG. 8 illustrates a setting for a DL DAI IE according to the relatedart.

Referring to FIG. 8, a bundling window consists of 4 DL subframes. In aDL subframe 0 810, the NodeB transmits a DL SA to a UE and sets the DLDAI IE value to V_(DAI) ^(DL)=1. In DL subframe 1 820, the NodeBtransmits a DL SA to the UE and sets the DL DAI IE value to V_(DAI)^(DL)=2. In DL subframe 2 830, the NodeB does not transmit a DL SA tothe UE, and thus, there is no DL DAI IE value. In DL subframe 3 840, theNodeB transmits PDSCH to the UE and sets the DL DAI IE value to V_(DAI)^(DL)=3. If the UE misses the DL SA in the last subframe, it cannot knowthis event and an erroneous operation occurs as the UE cannot report arespective DTX or NACK.

If a UE does not detect a DL SA transmitted by the NodeB in a subframeother than the last one in a bundling window and detects a DL SAtransmitted in a subsequent subframe in the same bundling window, it caninfer from the DL DAI IE value of the latter DL SA the number ofprevious DL SAs it has missed. The total number of DL SAs a UE detectsin a bundling window is denoted by U_(DAI). Therefore, a UE can knowthat it missed V_(DAI, last) ^(DL)−U_(DAI) DL SAs where V_(DAI, last)^(DL) is the DL DAI IE value in the last DL SA that the UE detects in abundling window. The actual number of DL SAs the UE may actually misscan be larger than V_(DAI, last) ^(DL)−U_(DAI). This happens if the UEmisses DL SAs after the last DL SA that it detects.

If a UE has a PUSCH transmission in an UL subframe where it alsotransmits HARQ-ACK information, the UE may transmit the HARQ-ACKinformation in the PUSCH. In order to avoid error cases where the UE hasmissed the last DL SA and in order to ensure the same understandingbetween the NodeB and the UE for the HARQ-ACK payload the UE transmitsin the PUSCH, a DAI IE is also included in the UL SA so that there is anUL DAI IE to indicate the HARQ-ACK payload. If the PUSCH transmission isnot associated with a UL SA, a UE assumes that there is a DL SA in everyDL subframe in the bundling window.

As for the DL DAI IE, the UL DAI IE value V_(DAI) ^(UL) is also assumedto be represented by 2 bits with the values of “00”, “01”, “10”, “11”respectively indicating V_(DAI) ^(UL)=1, V_(DAI) ^(UL)=2, V_(DAI)^(UL)=3, and V_(DAI) ^(UL)=4 or 0. The UL DAI IE bits “11” map toV_(DAI) ^(UL)=4 if the UE detects at least one DL SA in the bundlingwindow; otherwise, they map to V_(DAI) ^(UL)=0. In a case where thebundling window is larger than 4 subframes, the UL DAI IE value of “00”is assumed to indicate V_(DAI) ^(UL)=5 if 1<U_(DAI)≦5 or V_(DAI) ^(UL)=9if U_(DAI)>5. Similar, the UL DAI IE value of “01” is assumed toindicate V_(DAI) ^(UL)=6 if 2<U_(DAI)≦6, the UL DAI IE value of “10” isassumed to indicate V_(DAI) ^(UL)=7 if 3<U_(DAI)≦7, and the UL DAI IEvalue of “11” is assumed to indicate V_(DAI) ^(UL)=8 if 4<U_(DAI)≦8.

In order to increase peak data rates, the NodeB can configure a UE withCarrier Aggregation (CA) of multiple cells to provide higher operatingBWs. For example, in order to support communication over 60 MHz to a UE,a CA of three cells of 20 MHz each can be used. Assuming that the PDSCHin each cell conveys different TBs, the UE generates separate HARQ-ACKinformation for the respective TBs it receives in each cell. This issimilar to single-cell TDD operations, where the UE generates separateHARQ-ACK information for the respective TBs it receives in each DLsubframe for which the HARQ-ACK transmission is in the same UL subframe.

The NodeB, using higher layer signaling, can configure a set of C cellsto a UE and activate a subset of A cells (A≦C) for PDSCH reception in asubframe, using for example Medium Access Control (MAC) signaling,however a UE may not transmit or receive in inactive cells. If a PDSCHactivating or deactivating configured cells is missed, the UE and theNodeB may have a different understanding of the active cells. Moreover,in order to maintain communication, one cell with a DL/UL pair alwaysremains active and is referred to as a Primary cell (Pcell). PUCCHtransmissions from a UE are assumed to be only in its Pcell and HARQ-ACKinformation is conveyed only in a single PUSCH.

FIG. 9 illustrates a parallelization of the DL DAI IE design in FIG. 8for operation with multiple DL cells according to the related art.

Referring to FIG. 9, a NodeB transmits DL SAs to a UE in 3 DL subframesin Cell 0 910 and sets the respective DL DAI IE values according to thenumber of DL SAs transmitted to the UE only for PDSCH transmissions inCell 0 910. In a similar manner, the NodeB transmits DL SAs to the UE in2 DL subframes in Cell 1 920 and 2 DL subframes in Cell 2 930 and setsthe DL DAI IE values according to the number of DL SAs transmitted tothe UE only for PDSCH transmissions in Cell 1 920 and Cell 2 930,respectively.

Alternate designs to the parallelization of the DL DAI design for PDSCHtransmission in a single DL cell to multiple DL cells can be based on ajoint DL DAI design across DL cells and DL subframes. For each DLsubframe in the bundling window, the DL DAI counter operates first inthe cell-domain before continuing to the next DL subframe in thebundling window.

FIG. 10 illustrates an operation of a joint DL DAI design across cellsand DL subframes according to the related art.

Referring to FIG. 10, DL DAI IE values are shown only for DL subframesand configured DL cells where the NodeB transmits a DL SA to a UE. TheDL DAI counter starts from DL subframe 0 in Cell 0 1010 and continues inthe cell-domain DL subframe 0 for Cell 1 1020 and Cell 2 1030. After allDL SAs across the DL cells in DL subframe 0 are counted, the DL DAIcounter continues sequentially for the remaining DL subframes in thebundling window in the same manner as used for the DL subframe 0. ThisDL DAI IE is also assumed to consist of 2 bits mapping to the values ofV_(DAI) ^(DL)=1, 2, 3, 0. After V_(DAI) ^(DL)=3, the next value isV_(DAI) ^(DL)=0 because V_(DAI) ^(DL) is computed modulo 4.

For a UE is configured for communication over multiple DL cells, thefundamental conditions to properly convey HARQ-ACK information to theNodeB remain the same as for single-cell communication. In other words,for transmission of an HARQ-ACK payload of O_(HARQ-ACK) bits encodedwith a (32, O_(HARQ-ACK))RM code in a PUSCH, the UE and the NodeB shouldhave the same understanding of O_(HARQ-ACK). As the PUSCH transmissionpower is determined by assuming a data transmission and as thetransmission powers of HARQ-ACK REs and data REs are the same, theHARQ-ACK reception reliability depends on the number of respective PUSCHREs which scales linearly with O_(HARQ-ACK) as indicated in Equation(1). Therefore, whenever possible, O_(HARQ-ACK) should not be a maximumvalue in order to avoid unnecessarily consuming PUSCH REs.

For HARQ-ACK transmission in a PUCCH, since a UE may miss some DL SAs, acommon understanding for the HARQ-ACK payload between the UE and theNodeB is achieved only if the HARQ-ACK payload is always the maximumvalue of O_(HARQ-ACK) ^(max)=N_(bundle)·(C+C₂) bits or, withspatial-domain bundling, O_(HARQ-ACK) ^(max,bundle)=N_(bundle)·C bits,where N_(bundle) is the size of the bundling window, C is the number ofDL cells configured to the UE, and C₂ is the number of configured DLcells where the UE is configured a PDSCH Transmission Mode (TM)conveying 2 TBs.

Using the maximum HARQ-ACK payload in a PUCCH does not create additionalresource overhead. The UE may transmit a NACK or a DTX (in a case oftri-state HARQ-ACK information) for the TBs it did not receive, however,the NodeB already knows of the DL cells with no DL SA or PDSCHtransmission to the UE and can use the knowledge that the UE transmits aNACK for each of those DL cells (a priori information) to improve theHARQ-ACK reception reliability. This is possible because a linear blockcode and QPSK are assumed to be used for the encoding and modulation ofthe HARQ-ACK bits, respectively, and the NodeB can consider as candidateHARQ-ACK codewords only the ones having a NACK (binary ‘0’) at thepredetermined locations corresponding to cells without DL SAtransmissions to the UE. Due to the implementation of the decodingprocess, the use of the a priori information would be impractical orimpossible if a convolutional code or a turbo code was used for theencoding or if QAM was used for the modulation of the HARQ-ACK bits.

Although using the maximum HARQ-ACK payload for transmission in a PUCCHdoes not generate additional resource overhead, it often results in alarger transmission power than necessary for achieving the desiredreception reliability. PUCCH transmissions with larger power thannecessary increase UE power consumption and create additionalinterference degrading the reception reliability of signals transmittedby UEs in the same BW in other cells.

The PUCCH transmission power P_(PUCCH)(i) in UL subframe i is assumed tobe given as shown in equation (3), which is in units of decibels (dBs)per milliwatt (dBm).

P _(PUCCH)(i)=min{P _(CMAX,c) ,h(n _(HARQ-ACK)(i))+F(i)}  Equation (3)

where P_(CMAX,c) is the maximum allowed UE transmission power in itsPcell, h(n_(HARQ-ACK)(i)) is a monotonically increasing function of then_(HARQ-ACK)(i) HARQ-ACK information bits the UE assumes it istransmitting, and F(i) is a general function capturing all otherparameters affecting P_(PUCCH)(i) in UL subframe i. However, the presentinvention is not limited to the exact expression of h(n_(HARQ-ACK)(i)),for example, it may be determined as h(n_(HARQ-ACK)(i))=α·10 log10(n_(HARQ-ACK)(i)), with α being a positive number, orh(n_(HARQ-ACK)(i)) can be provided by a table indicating thetransmission power as function of n_(HARQ-ACK)(i). It is noted that theabove expression does not account for possible multiplexing with theHARQ-ACK of additional information, such as a Service Request Indicator(SRI) used by a UE to indicate it has data to transmit. The key issue isfor a UE to determine the proper n_(HARQ-ACK) value. If n_(HARQ-ACK) istoo small the HARQ-ACK reception reliability is degraded. Ifn_(HARQ-ACK) is too large, interference and UE battery consumptionincrease unnecessarily.

One possibility is for n_(HARQ-ACK)(i) to be equal to the number of TBsthe UE receives in a respective bundling window. This avoids excessivetransmission power, but may underestimate the required transmissionpower as some DL SAs may be missed, thereby decreasing the HARQ-ACKreception reliability. Another possibility is to derive n_(HARQ-ACK)(i)from the maximum HARQ-ACK payload as n_(HARQ-ACQ)(i)=N_(bundle)·(C+C₂).This ensures that the required HARQ-ACK reception reliability is alwaysmet, but will often result to the transmission power being excessivelylarge. A variation of the second possibility is to consider only thenumber of activated cells A and the configured TM in each such cell.Then, n_(HARQ-ACQ)(i)=N_(bundle)·(A+A₂) where A₂ is the number ofactivated cells with a configured TM conveying 2 TBs. However, excessivetransmission power is again not avoided as not all active cells maytransmit PDSCH to the UE in every DL subframe in the bundling window.

Therefore, there is a need to set the HARQ-ACK transmission power in aPUCCH while achieving the desired HARQ-ACK reception reliability in caseof DL CA for a TDD system.

There is also a need to set the HARQ-ACK transmission power in the PUCCHwhile minimizing interference and UE power consumption in case of DL CAfor a TDD system.

There is also a need to establish a common understanding between the UEand the NodeB about the correspondence between the HARQ-ACK informationbits in the transmitted codeword and the respective cells and subframesin the case of a DL CA for a TDD system.

Finally, there is also a need to minimize the number of PUSCH REsallocated to HARQ-ACK transmission in case of DL CA for a TDD system.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide methods and apparatus for a UE operating in aTDD communication system and configured to have multiple DL cells todetermine the HARQ-ACK payload for transmission in a PUSCH and theHARQ-ACK signal transmission power for transmission in a PUCCH whileconsidering the presence and design of a DAI IE in DCI formatsscheduling PDSCH receptions by the UE and the presence and design of aDAI IE in DCI formats scheduling PUSCH transmissions by the UE.

In accordance with an aspect of the present invention, a UE determinesthe transmission power of HARQ-ACK signal transmission in a PUCCH bydetermining a parameter that is the sum of two components. The firstcomponent is equal to a number of TBs received through all configured DLcells and through all DL subframes in the bundling window and does notdepend on the transmission mode that the UE is configured to have forPUSCH reception in a respective DL cell. The second component is equalto a number of TBs that the UE did not receive but which it can identifyas missed. The UE, using the DL DAI IE values in the DL SAs that itdetects, can determine a number of PDSCH that the UE missed in eachconfigured DL cell, although the UE may not necessarily determine allPDSCH that it missed. Then, depending on the respective configured PDSCHtransmission mode in each configured DL cell, the UE identifies that itmissed PDSCH, and thus, the UE computes a number of TBs assuming thateach missed PDSCH conveyed a number of TBs determined by the respectiveconfigured transmission mode.

In accordance with another aspect of the present invention, a UEdetermines the HARQ-ACK payload for multiplexing in a PUSCH depending onwhether the PUSCH is scheduled by an UL SA. If the PUSCH is notscheduled by an UL SA, the UE multiplexes the maximum HARQ-ACK payload,which is equal to the sum of the number of configured DL cells and thenumber of configured DL cells, with a configured PDSCH transmission modethat enables the transmission of 2 TBs multiplied by a size of thebundling window. If the PUSCH is scheduled by an UL SA, the UE considersthat the UL DAI IE value of the UL SA is applicable over all configuredDL cells and indicates the number of PDSCH transmitted to the UE in eachof the configured DL cells. Then, for each of the configured DL cells,the HARQ-ACK payload that the UE generates is equal to the number of TBsassociated with the respective configured transmission mode for thePDSCH multiplied by the size of the bundling window.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following description taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating a frame structure for a TDD systemaccording to the related art;

FIG. 2 is a diagram illustrating a PUSCH transmission structureaccording to the related art;

FIG. 3 is a block diagram illustrating a transmitter for transmittingdata information and HARQ-ACK information in a PUSCH according to therelated art;

FIG. 4 is a block diagram illustrating a receiver for receiving datainformation and HARQ-ACK information in a PUSCH according to the relatedart;

FIG. 5 is a diagram illustrating a PUCCH structure for the transmissionof multiple HARQ-ACK information bits using the DFT-S-OFDM transmissionmethod according to the related art;

FIG. 6 is a block diagram illustrating a transmitter for transmittingHARQ-ACK information in a PUCCH according to the related art;

FIG. 7 is a block diagram illustrating a receiver for receiving dataHARQ-ACK information in a PUCCH according to the related art;

FIG. 8 is a diagram illustrating a setting for a DL DAI IE according tothe related art;

FIG. 9 is a diagram illustrating a parallelization of the DL DAI IEdesign in FIG. 8 for operation with multiple cells according to therelated art;

FIG. 10 is a diagram illustrating an operation of a joint DL DAI designacross cells and DL subframes according to the related art;

FIG. 11 is a diagram illustrating a process for a UE configured withmultiple DL cells to determine missed DL SAs assuming the directparallelization of the DL DAI design in FIG. 9 to multiple DL cellsaccording to an exemplary embodiment of the present invention;

FIG. 12 is a diagram illustrating a process for a UE configured withmultiple DL cells to determine missed DL SAs for the DL DAI operation inmultiple DL cells as in FIG. 10 according to an exemplary embodiment ofthe present invention;

FIG. 13 is a diagram illustrating an example of a UE configured withmultiple DL cells not being able to determine which DL SAs it missed incase of the DL DAI design as in FIG. 10 according to an exemplaryembodiment of the present invention;

FIG. 14 is a diagram illustrating a process for a UE configured withmultiple DL cells to determine the HARQ-ACK payload for the DL DAIdesign in FIG. 10 according to an exemplary embodiment of the presentinvention;

FIG. 15 is a diagram illustrating the inability of the related artinterpretation of a UL DAI IE in an UL SA to indicate the HARQ-ACKpayload a UE should transmit in a respective PUSCH is response to thereception of multiple PDSCH over a bundling window in respectivemultiple cells for the DL DAI design in FIG. 9 based on the setup ofFIG. 11 according to an exemplary embodiment of the present invention;and

FIG. 16 is a diagram the use of the UL DAI IE in a UL SA for a PUSCHwhere a UE multiplexes HARQ-ACK information to determine the HARQ-ACKpayload and ordering for the DL DAI design in FIG. 9 or in FIG. 10according to an exemplary embodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Additionally, although exemplary embodiments of the present inventionwill be described below with reference to Discrete Fourier Transform(DFT)-spread Orthogonal Frequency Division Multiplexing (OFDM)transmission, the exemplary embodiments of the present invention arealso applicable to all Frequency Division Multiplexing (FDM)transmissions in general and to Single-Carrier Frequency DivisionMultiple Access (SC-FDMA) and OFDM in particular.

In all subsequent descriptions, a User Equipment (UE) is assumed togenerate Hybrid Automatic Repeat reQuest (HARQ)-ACKnowledgement (ACK)information in response to each Transmission Block (TB) associated witha DownLink (DL) Scheduling Assignment (SA). However, a UE may alsodeterministically generate HARQ-ACK information associated with eachSemi-Persistent Scheduling (SPS) TB the NodeB transmits at predeterminedDL subframes without transmitting a respective DL SA. In the remainingTBs, it is understood that the UE includes HARQ-ACK information due toSPS, when it exists, with the HARQ-ACK information it generates inresponse to DL SAs and a placement of the HARQ-ACK information can be,for example, in the beginning of the overall HARQ-ACK payload. Furtherexplicit reference to HARQ-ACK information in response to SPS TBs isomitted for brevity. Moreover, in the case of a DL SA not beingassociated with a respective PDSCH (and data TBs), but instead beingused to serve other purposes, will also not be explicitly considered.However, a UE is assumed to generate a HARQ-ACK information bitcorresponding to such DL SA. The descriptions of the exemplaryembodiments consider the configured cells but the same argumentsdirectly apply if the activated cells are instead considered.

An exemplary embodiment of the present invention describes a method fora UE to determine the transmission power of its HARQ-ACK signal in aPhysical Uplink Control Channel (PUCCH) for a Time-Division Duplex (TDD)system using DL Carrier Aggregation (CA). The UE is to determine theparameter n_(HARQ-ACK)(i) used in the Transmit Power Control (TPC)formula in Equation (3) (for simplicity, an UpLink (UL) subframe index iis omitted in the following analysis).

The first step for determining n_(HARQ-ACK) is to determine a firstcomponent consisting of the number of HARQ-ACK information bits derivedfrom the received TBs in the DL subframe bundling window, n_(HARQ-ACK)^(rTBs), without considering the respective configured Physical DownlinkShared CHannel (PDSCH) Transmission Mode (TM). Consequently, even thougha UE may be configured to be in a Single User-Multiple Input MultipleOutput (SU-MIMO) TM enabling transmission of 2 TBs in a PDSCH from theNodeB to the UE in a cell, the transmission power accounts for 1HARQ-ACK bit if the PDSCH reception actually conveys only 1 TB.Therefore, the PUCCH transmission power does not depend on theconfigured PDSCH TM for each cell but depends on the number of receivedTBs in that cell. Denoting as R the total number of received TBs in theconfigured cells over a bundling window of N_(bundle) DL subframes,

$N^{received} = {\sum\limits_{c = 0}^{C - 1}{\sum\limits_{m = 0}^{N_{bundle} - 1}{N^{received}( {m,c} )}}}$

where N^(received)(m,c) is the number of received TBs in configured cellc in DL subframe m of the bundling window, the total number of HARQ-ACKbits corresponding to received TBs is

n _(HARQ-ACK) ^(rTBs) =N ^(received)  Equation (4)

The second step in determining the value of n_(HARQ-ACK) is todetermine, based on the DL DAI IE, a second component consisting ofHARQ-ACK bits corresponding to TBs that were not received, but which canbe inferred by a UE as being transmitted by the NodeB using the DL DAIIE in order to determine the PDSCH receptions that the UE has missed. Asthe UE may not know the number of TBs conveyed by a missed PDSCHreception (i.e., 1 TB or 2 TBs were conveyed), the respective number ofHARQ-ACK bits considers the configured PDSCH TM in the respective cellof the missed DL SA that the UE identified in order to provide aconservative estimate and always ensure that the HARQ-ACK receptionreliability is achieved in a case where the configured PDSCH TM enabledtransmission of the 2 TBs to the UE. Therefore, if a UE determines thatit missed a total of N_(DLSA) ^(missed) DL SAs where N_(DLSA,2)^(missed) of those DL SAs are in DL cells where the UE has a configuredPDSCH TM enabling transmission of 2 TBs, the UE determines the number ofrespective HARQ-ACK bits as

n _(HARQ-ACK) ^(mTBs) =N _(DLSA) ^(missed) +N _(DLSA,3)^(missed)  Equation (5)

Then, n_(HARQ-ACK) is obtained as

n _(HARQ-ACK) =n _(HARQ-ACK) ^(rTBs) +n _(HARQ-ACK) ^(mTBs) =N^(received) +N _(DLSA) ^(missed) +N _(DLSA,2) ^(missed)  Equation (6)

If spatial bundling applies, then

n _(HARQ-ACK) =N _(DLSA) ^(received) +N _(DLSA) ^(missed)  Equation (7)

where N_(DLSA) ^(received) is the number of DL SAs detected by the UE.Including SPS PDSCH as previously mentioned, n_(HARQ-ACK)=N_(DLSA)^(received)+N_(DLSA) ^(missed)+N_(PDSCH) ^(SPS).

For the DL DAI IE design in FIG. 7, n_(HARQ-ACK) can be equivalentlyobtained as

$\begin{matrix}{n_{{HARQ}\text{-}{ACK}} = {\sum\limits_{c = 0}^{C - 1}{\sum\limits_{m = 1}^{V_{{DL},{last}}^{DAI}{(c)}}{{TB}( {m,c} )}}}} & {{Equation}\mspace{14mu} (8)}\end{matrix}$

where V_(DAI, last) ^(DL)(c) is the DL DAI IE value in the last DL SAthat the UE successfully receives in cell c, and TB(m,c) is the numberof TBs that the UE receives in cell c and subframe j in the bundlingwindow. For a DL subframe m and cell c where the UE misses the DL SA,TB(m,c) is determined by the maximum number of TBs associated with theconfigured TM in cell c, TB_(max)(c). As the DL DAI IE design in FIG. 7is a counter of DL SAs transmitted per cell to a UE, Equation (8) isequivalent to

$n_{{HARQ}\text{-}{ACK}} = {\sum\limits_{c = 0}^{C - 1}\begin{pmatrix}{( {{V_{{DAI},{last}}^{DL}(c)} - {U_{DAI}(c)}} ) \cdot} \\{{{TB}_{{ma}\; x}(c)} + {\sum\limits_{m = 0}^{N_{bundle} - 1}{N^{received}( {m,c} )}}}\end{pmatrix}}$

where U_(DAI)(c) is the total number of DL SAs the UE detects in cell cduring the bundling window. The UE knows it misses V_(DAI, last)^(DL)(c)−U_(DAI)(c) DL SAs in cell c. If spatial bundling is applied,TB(m,c)=1 and

$n_{{HARQ}\text{-}{ACK}} = {\overset{C - 1}{\sum\limits_{c = 0}}{\begin{pmatrix}{( {{V_{{DAI},{last}}^{DL}(c)} - {U_{DAI}(c)}} ) +} \\{\sum\limits_{m = 0}^{N_{bundle} - 1}{N_{DLSA}^{received}( {m,c} )}}\end{pmatrix}.}}$

In a case where the number of TBs does not vary per DL subframe in cellc, or in other words, the number of TBs is always equal to the number ofTBs for the configured TM, then

${{U_{DAI}(c)} \cdot {{TB}_{\max}(c)}} = {\sum\limits_{m = 0}^{N_{bundle} - 1}\; {N^{received}( {m,c} )}}$

and Equation (8) can be simplified as

$\begin{matrix}{n_{{HARQ}\text{-}{ACK}} = {\sum\limits_{c = 0}^{C - 1}{{V_{{DL},{last}}^{DAI}(c)} \cdot {{TB}(c)}}}} & {{Equation}\mspace{14mu} (9)}\end{matrix}$

FIG. 11 illustrates a process for a UE configured with multiple DL cellsto determine missed DL SAs assuming the direct parallelization of the DLDAI design in FIG. 9 to multiple DL cells according to an exemplaryembodiment of the present invention.

Referring to FIG. 11, for C=3 configured cells and for a bundling windowsize of N_(bundle)=4 subframes, a UE determines the N_(DLSA) ^(missed)missed DL SAs by counting their number based on the DL DAI IE values inthe DL SAs it receives. In Cell 0 1110, the UE misses the DL SA in DLsubframe 1 and it becomes aware of this event based on the DL DAI IEvalue V_(DAI,last) ^(DL)(0) in DL subframe 3, wherein the DL DAI IEvalue is V_(DAI,last) ^(DL)(0)=3, and U_(DAI)(0)=2. In Cell 1 1120, theUE misses the DL SA in DL subframe 3 but cannot become aware of thisevent as DL subframe 3 is the last subframe of the bundling window,wherein the DL DAI IE value is V_(DAI,last) ^(DL)(1)=1, andU_(DAI)(1)=1. In Cell 2 1130, the UE misses the DL SA in DL subframe 1and it becomes aware of this event based on the DL DAI IE valueV_(DAI,last) ^(DL)(2) in DL subframe 2, wherein the DL DAI IE value isV_(DAI,last) ^(DL)(2)=2, and U_(DAI)(2)=1. Therefore, the UE determinesthat it missed N_(DLSA) ^(missed)=2 DL SAs, wherein

$N_{DLSA}^{missed} = {\sum\limits_{c = 0}^{2}\; ( {{{V_{{DAI},{last}}^{DL}(c)} - {U_{DAI}(c)}},} }$

even though it missed 3 DL SAs and it also determines the respectivecells of the 3 missed DL SAs.

Furthermore, if in Cell 0 the UE is configured with a TM enablingtransmission of 2 TBs (TB_(max)(0)=2) and in Cell 2 the UE is configuredwith a TM enabling transmission of 1 TB (TB_(max)(2)=1) the UE assumesthat the total number of missed TBs is 3 (2 TBs in Cell 0 and 1 TB inCell 2). Therefore, in addition to the received TBs, the UE, for thedetermination of n_(HARQ-ACK), considers the

$\begin{matrix}{n_{{HARQ}\text{-}{ACK}}^{mTBs} = {N_{DLSA}^{missed} + N_{{DLSA},2}^{missed}}} \\{= 3} \\{= {\sum\limits_{c = 0}^{2}\; {( {{V_{{DAI},{last}}^{DL}(c)} - {U_{DAI}(c)}} ) \cdot {{TB}_{\max}(c)}}}}\end{matrix}$

TBs the UE identified as missed. In FIG. 11, the UE receives 2 TBs in DLsubframe 0 and 2 TBs in DL subframe 3 in Cell 0, 1 TB in DL subframe 3in Cell 1, and 1 TB in DL subframe 2 of Cell 2. Therefore, the totalnumber of received TBs and the respective number of HARQ-ACK bits isn_(HARQ-ACK) ^(rTBs)=N^(received)=6. Therefore, n_(HARQ-ACK)=9.

For the DL DAI IE design in FIG. 10, n_(HARQ-ACK) can be equivalentlyobtained as

n _(HARQ-ACK) =N ^(received) +N _(DLSA) ^(missed) ·TB _(max)  Equation(10)

where TB_(max) is the maximum number of TBs the UE is enabled to receivefrom the configured TM in any of the cells. If spatial bundling applies,then TB_(max)=1. Therefore, N_(DLSA,2) ^(missed)=N_(DLSA) ^(missed) ifTB_(max)=2 and N_(DLSA,2) ^(missed)=0 if TB_(max)=1. If, due to themodulo operation, the UE identifies that the DL DAI is reset N_(reset)times, thenn_(HARQ-ACK)=N^(received)+(N_(reset)·N_(bundle)+V_(DAI, last)^(DL)−U_(DAI))·TB_(max) where V_(DAI, last) ^(DL) is the last DL DAI IEvalue for the design in FIG. 10 and U_(DAI) is the number of DL SAs theUE detected across all cells and DL subframes in the bundling window ofsize N_(bundle). If spatial bundling is used, then N^(received)=U_(DAI)and n_(HARQ-ACK)=N_(reset)·N_(bundle)+V_(DAI, last) ^(DL).

FIG. 12 illustrates a process for a UE configured with multiple DL cellsto determine missed DL SAs for the DL DAI operation in multiple DL cellsas in FIG. 10 according to an exemplary embodiment of the presentinvention.

Referring to FIG. 12, in Cell 0 1210, the UE misses the DL SA in DLsubframe 1 and it becomes aware of a missed DL SA (although, the UE doesnot necessarily become aware of the actual missed DL SA) based on the DLDAI IE value in DL subframe 1 1222 of Cell 1 1220. In Cell 2 1230, theUE misses the DL SA in DL subframe 1 and becomes aware a missed DL SA(again, not necessarily of the actual missed one) based on the DL DAI IEvalue in DL subframe 2 1232 of Cell 2. Finally, in Cell 1, the UE missesthe DL SA in DL subframe 3 but it cannot become aware of this eventsince it is the last DL SA the NodeB transmits to the UE.

For the DL DAI IE design in FIG. 10, although the UE can identify themissed DL SAs, except for the last one, it may not be able to determinethe respective cells. Therefore, the UE may not be able to know thenumber of TBs it missed and, if spatial bundling is not used, it may notbe able to know the respective number of HARQ-ACK bits or the value ofn_(HARQ-ACK).

For example, in FIG. 12, the UE cannot know whether the DL SA that wasmissed in DL subframe 1 of Cell 0 was not transmitted in DL subframe 0of Cell 1 or Cell 2. As in Cell 0, Cell 1, and Cell 2, the UE hasconfigured TMs enabling transmission for a maximum of 2 TBs, 1 TB, and 1TB, respectively, and the UE needs to assume that it missed the DL SA inCell 0 in order to avoid underestimating the HARQ-ACK signaltransmission power in the PUCCH. Then, as the UE assumes it missed 2TBs, N_(DLSA,2) ^(missed)=N_(DLSA) ^(missed)=2, the UE considers thatthe total number of missed TBs is 4. Therefore, the UE additionallyconsiders n_(HARQ-ACK) ^(mTBs)=N_(DLSA) ^(missed)+N_(DLSA,2) ^(missed)=4TBs (HARQ-ACK bits) in the determination of n_(HARQ-ACK) and theHARQ-ACK signal transmission power in the PUCCH. The remaining TBs(i.e., the HARQ-ACK bits) used to determine n_(HARQ-ACK) and theHARQ-ACK signal transmission power in the PUCCH are based on thereceived TBs.

In FIG. 12, the UE receives 2 TBs in DL subframe 0 and 2 TBs in DLsubframe 3 in Cell 0, 1 TB in DL subframe 3 in Cell 1, and 1 TB in DLsubframe 2 of Cell 2 for a total number of n_(HARQ-ACK)^(rTBs)=N^(received)=6 TBs (HARQ-ACK bits). Therefore, n_(HARQ-ACK)=10.

The exemplary embodiments in FIG. 11 and FIG. 12 are only illustrativeof two DL DAI designs and are not meant to be exclusive of otherdesigns, but rather the exemplary embodiments are meant to illustratethe use of DL DAI IE in determining the HARQ-ACK payload that the UEassumes when setting the transmission power of the HARQ-ACK signal inthe PUCCH. For example, the first component may be based on the numberof configured or activated cells instead of the number of received TBs.

Based on the previous analysis, alternative approaches for a UE todecide the number of TBs contained in missed DL SAs can be devised in astraightforward manner. For example, the UE may assume that each missedDL SA conveyed 1 TB, in order to avoid HARQ-ACK signal transmission inthe PUCCH with larger power than necessary. Alternatively, the UE mayassume that in a case where it has a configured TM enabling thetransmission of 2 TBs in any cell, half of the missed PDSCH receptionsconvey 2 TBs and the other half convey 1 TB (with priority given to 2TBs in case of an odd number of missed DL SAs). Then, n_(HARQ-ACK)^(mTBs)=N_(DLSA) ^(missed)+┌N_(DLSA,2) ^(missed)/2┐.

In a case where the DL DAI design cannot provide information to the UEabout whether a DL SA in the last DL subframe of the bundling window ismissed, the UE may assume one or two additional TBs (depending on theconfigured TM in the respective cell) when determining n_(HARQ-ACK)^(mTBs) if the UE does not receive a DL SA in the last DL subframe ofthe bundling window. Then, n_(HARQ-ACK)=n_(HARQ-ACK)^(rTBs)+n_(HARQ-ACK) ^(mTBs)+Q_(last) where, for example, Q_(last)=2 ifthe UE has a configured TM enabling the transmission of 2 TBs; otherwiseQ_(last)=1. In a case where multiple DL subframes may be missed, thenthe Q_(last) value may be scaled accordingly. In this manner, the UEdoes not underestimate the required HARQ-ACK signal transmission powerin the PUCCH. The number of DL subframes that should be accounted for byQ_(last) may be predetermined or configured for the UE by the NodeB.

Another exemplary embodiment of the present invention considers thedetermination of the HARQ-ACK payload in a PUSCH in order for a UE and aNodeB to achieve the same understanding of the transmitted HARQ-ACKinformation. In all subsequent descriptions, a UE is assumed to generatean ACK or a NACK depending on the reception outcome (correct orincorrect) of each respective TB it receives and to generate a NACK foreach TB it identifies as missed. First, a case where no UL SA existswill be discussed below.

As previously noted, for the DL DAI design in FIG. 9, if a UE misses aDL SA in the last DL subframe of the bundling window of each cell, theUE cannot be aware of this event. Therefore, if the HARQ-ACK payload isdetermined from the number of received TBs, or received DL SAs, thiswould result in erroneous operation as a UE will not include therespective HARQ-ACK bits in the total HARQ-ACK payload and the NodeBcannot know of the UE missing a DL SA in the last DL subframe. To avoidthis erroneous operation, a UE may generate a NACK for each TB (or formultiple TBs in a case of spatial bundling) of each DL subframe in whichit did not receive a DL SA. The trade-off for ensuring proper operationin this manner is the increased HARQ-ACK payload as a NACK is generatedfor each TB of a DL subframe when the NodeB does not transmit a DL SA tothe UE. Then, for N_(bundle) DL subframes in the bundling window, theHARQ-ACK payload is

$\begin{matrix}{O_{{HARQ}\text{-}{ACK}} = {{N_{bundle} \cdot {\sum\limits_{c = 0}^{C - 1}{{TB}_{{ma}\; x}(c)}}} = {N_{bundle} \cdot ( {C + C_{2}} )}}} & {{Equation}\mspace{14mu} (11)}\end{matrix}$

where C is the number of configured cells, C₂ is the number ofconfigured cells with a configured TM enabling the reception of 2 TBsfor the reference UE, and TB_(max)(c) is the maximum number of TBs theUE is configured to receive in cell c. If spatial bundling is used, thenO_(HARQ-ACK)=N_(bundle)·C. As a DL DAI IE is not used in this case, theabove is applicable to any DL DAI design.

The HARQ-ACK payload in a PUSCH, according to Equation (11), is alwaysthe maximum possible value and methods for its possible reduction may beconsidered.

For the DL DAI design illustrated in FIG. 10, unless spatial bundling isused, the determination of the HARQ-ACK payload is problematic becausethe DL DAI design in FIG. 10 is across cells where a UE may beconfigured for TMs enabling reception for different numbers of TBs (1 or2) and neither the NodeB nor the UE can know which DL SAs were missed.In other words, the UE may have different TMs for different cells,enabling reception for different numbers of TBs in the cells.

FIG. 13 illustrates an example of a UE configured with multiple DL cellsnot being able to determine which DL SAs it missed in case of the DL DAIdesign in FIG. 10 according to an exemplary embodiment of the presentinvention.

Referring to FIG. 13, a UE is configured with a TM enabling thereception of 2 TBs per subframe in Cell 0 1310 and with a TM enablingthe reception of 1 TB per subframe in Cell 1 1320 and Cell 2 1330. In DLsubframe 1, the UE receives a DL SA in Cell 1, and based on the DAI IEvalue 1322 it becomes aware of a missed DL SA, which, as shown in FIG.13, is missed DL SA 1215. However, as the UE cannot know whether the DLSA that it missed was in Cell 0, Cell 1, or Cell 2, there are twopossible assumptions the UE can make; either 2 TBs were missed or 1 TBwas missed. The former is the correct assumption, while the latter isincorrect and will lead to a misunderstanding of the HARQ-ACK payloadbetween the UE and the NodeB. In DL subframe 2, the UE receives a DL SAin Cell 2 and based on the DAI IE value 1332 it becomes aware that itmissed another DL SA, which, as shown in FIG. 13, is missed DL SA 1325.As the UE cannot know whether the DL SA it missed was in Cell 0, Cell 1,or Cell 2, there are again two possible assumptions the UE can make;either the UE missed 2 TBs or the UE missed 1 TB. The latter is thecorrect assumption while the former is incorrect and will lead to amisunderstanding between the UE and the NodeB of the HARQ-ACK payload.Obviously, if the UE generates HARQ-ACK bits according to the configuredTM in each cell, it is not possible to achieve the same understanding ofthe HARQ-ACK payload between the NodeB and the UE when DL SAs aremissed.

In order to achieve the same understanding at a UE and the NodeB for thepayload and proper ordering of the HARQ-ACK bits, the UE should alwaysgenerate HARQ-ACK bits corresponding to the TM enabling reception forthe largest number of TBs regardless of the TM configured in aparticular cell.

FIG. 14 illustrates a process for a UE configured with multiple DL cellsto determine the HARQ-ACK payload for the DL DAI design in FIG. 10according to an exemplary embodiment of the present invention.

Referring to FIG. 14, a UE is configured to have a TM enabling thereception of 2 TBs per subframe in Cell 0 1410 and a TM enabling thereception of 1 TB per subframe in Cell 1 1420, Cell 2 1430, and Cell 31440. As the UE is configured to have a TM enabling reception of 2 TBsin at least one cell, it generates 2 HARQ-ACK bits for every DL SA itidentifies regardless of the TM of the respective cell. In DL subframe0, the UE receives a DL SA for Cell 0 and generates 2 respectiveHARQ-ACK bits b0, b1 1415. In DL subframe 1, the UE receives a DL SA forCell 1, and based on the respective DL DAI IE value 1422 the UEdetermines that there was a missed DL SA. Then, the UE generates 4respective HARQ-ACK bits b2, b3, b4, b5 1425. In DL subframe 2, the UEreceives a DL SA for Cell 3, and based on the respective DL DAI IE value1432, the UE determines that there was a missed DL SA. Then, the UEgenerates 4 respective HARQ-ACK bits b6, b7, b8, b9 1435. Finally, in DLsubframe 3, the UE receives a DL SA for Cell 0 but also generates 2additional HARQ-ACK bits in case the UE missed a next DL SA at the endof a cell. Therefore, the UE generates 4 respective HARQ-ACK bits b10,b11, b12, b13 1445. This assumes that a probability that the UE missesmore than one of the last DL SAs at the end of a cell is negligible.Otherwise, the UE may generate multiple pairs of HARQ-ACK bitscorresponding to the multiple possible missed DL SAs after the lastmissed DL SA that the UE was aware of, as previously discussed above.

Assuming that a UE can determine N_(DAI) ^(DL) DL SAs based on the DLDAI IE values, N_(DAI) ^(DL)=N_(reset)·N_(bundle)+V_(DAI, last) ^(DL),and by denoting TB_(max) to be the maximum number of TBs for anyconfigured TM in any cell (wherein TB_(max) is 1 or 2, and whereinTB_(max) is always 1 if spatial bundling is applied) and by Q_(add)being the number of additional DL SAs assumed to have been missed by theUE after the last received DL SA (it is noted that Q_(add) may beconfigured for the UE by the NodeB and appropriately reduced if the UEcorrectly receives Q_(add) or less of the last DL SAs), then theHARQ-ACK payload is (assuming that DTX is mapped to a NACK) given byEquation (12).

O _(HARQ-ACK)=(N _(DAI) ^(DL) +Q _(add))·TB _(max)  Equation (12)

As the HARQ-ACK payload in Equation (12) may be smaller than the one inEquation (11), particularly if spatial domain bundling is applied,Equation (12) may be used to determine the HARQ-ACK payload in a casewhere the transmission is in the PUSCH.

The approach used in Equation (12) can also be followed for the DL DAIdesign in FIG. 9 in order to reduce the HARQ-ACK payload compared toEquation (11), assuming that the probability of the UE missing 2consecutive DL SAs is negligible. Thus, the HARQ-ACK payload is given byEquation (13).

$\begin{matrix}{O_{{HARQ}\text{-}{ACK}} = {{\sum\limits_{c = 0}^{C - 1}{( {{N_{DAI}^{DL}(c)} + {Q_{add}(c)}} ) \cdot {{TB}_{{ma}\; x}(c)}}} = {\sum\limits_{c = 0}^{C - 1}{( {{V_{{DAI},{last}}^{DL}(c)} + {Q_{add}(c)}} ) \cdot {{TB}_{{config}\;}(c)}}}}} & {{Equation}\mspace{14mu} (13)}\end{matrix}$

where N_(DAI) ^(DL)(c)=V_(DAI, last) ^(DL)(c) is the number of DL SAsthat the UE determines to be transmitted from the NodeB during thebundling window in cell c, wherein Q_(add)(c)=0 if the DL SA in the lastDL subframe of cell c is correctly received while Q_(add)(c)=1otherwise. Therefore, for the DL DAI design in FIG. 9, the UE willgenerate HARQ-ACK information for 3 DL SAs in Cell 0, for 2 DL SAs inCell 1, and for 3 DL SAs in Cell 2, and the same understanding exists atthe NodeB.

Next, a case wherein the UL SA exists will be discussed. If a UEreceives an UL SA for a PUSCH transmission in the same UL subframe asthe expected HARQ-ACK signal transmission, and the HARQ-ACK informationis included in that PUSCH, the related art UL DAI IE cannot be directlyre-used as it corresponds only to a single cell and PUSCH transmissionmay not exist in all cells.

FIG. 15 illustrates the inability of the related art interpretation of aUL DAI IE in an UL SA to indicate the HARQ-ACK payload a UE shouldtransmit in a respective PUSCH is response to the reception of multiplePDSCH over a bundling window in respective multiple cells for the DL DAIdesign in FIG. 9 based on the setup of FIG. 11 according to an exemplaryembodiment of the present invention. The same arguments apply for the DLDAI design in FIG. 10.

Referring to FIG. 15, in Cell 0 1510, a UE receives an UL SA with an ULDAI IE indicating that the UE needs to include HARQ-ACK bitscorresponding to 3 DL SAs, V_(DAI) ^(UL)=3. As Cell 0 is assumed to beconfigured to have a TM enabling reception of 2 TBs, then, if spatialbundling does not apply, the interpretation of the UL DAI IE should befor multiples of 2 HARQ-ACK bits per DL SA and therefore a value ofV_(DAI) ^(UL)=3 indicates 6 HARQ-ACK bits to be included in the PUSCHtransmission. Nevertheless, as in Cell 1 1520 and Cell 2 1530 the UEdoes not receive a UL SA 1525 and 1535, respectively, the UL DAI IEreceived in Cell 0 cannot serve the purpose of informing the UE of thenumber of HARQ-ACK bits it needs to include in the respective PUSCHtransmission.

One approach to circumvent the limitations of the related art UL DAI IE,in a case of DL CA, is to consider application of the UL DAI IE over allcells under the assumption that the probability that the UE misses 4 ormore DL SAs is negligible (the UL DAI IE is assumed to consist of 2bits). Then, the interpretation of the UL DAI IE may be consideredjointly with the DL DAI IE values.

For the DL DAI design of FIG. 13, based on the DL DAI IE values in Cell0, a UE knows that NodeB transmitted 2 DL SAs to the UE. Based on the DLDAI IE values in Cell 1, the UE knows that the NodeB transmitted 1 DLSA, that the UE missed 1 DL SA, and the UE cannot be aware of the missedDL SA in the last DL subframe of the bundling window. Based on the DLDAI IE in Cell 2, the UE knows that the NodeB transmitted 1 DL SA andthat the UE missed 1 DL SA. Therefore, the UE can know that the NodeBtransmitted 6 DL SAs and that 2 of them were missed by the UE.

The UL DAI IE value is effectively interpreted modulo 4 (assuming 4 DLsubframes in the bundling window) and a value of V_(DAI) ^(UL)=3indicates that either 3, or 7 DL SAs were transmitted by the NodeB tothe UE. Therefore, if from the DL DAI IE, the UE determines that theNodeB transmitted 6 DL SAs, a value of V_(DAI) ^(UL)=3 is interpreted asindicating that the NodeB transmitted 7 DL SAs to the UE. If the UE candetermine, based on the DL DAI IE values, that the NodeB transmittedN_(DAI) ^(DL) DL SAs to the UE, and the UE is informed of V_(DAI) ^(UL)DL SAs through the UL DAI IE value, then the UE determines the totalnumber N_(SA,total) ^(DL) of DL SAs the NodeB transmitted to the UE asgiven in Equation (14).

N _(SA, total) ^(DL) =N _(DAI) ^(DL) +V _(DAI) ^(UL)−mod(N _(DAI)^(DL),4)  Equation (14)

Although the above described approach can identify the total number ofDL SAs that the NodeB transmits to the UE, it is still inadequate foridentifying a proper placement of the HARQ-ACK bits in the transmittedcodeword. For example, in FIG. 15, although the UE can identify that itmissed a DL SA, it cannot identify whether this DL SA was in the last DLsubframe of Cell 1 or in the last DL subframe of Cell 2, andconsequently it cannot know the proper ordering for the HARQ-ACKinformation unless the HARQ-ACK information is assumed to apply for allcells, as shown in Equation (15).

O _(HARQ-ACK)=(N _(DAI) ^(DL) +V _(DAI) ^(UL)−mod(N _(DAI) ^(DL),4))·TB_(max)  Equation (15)

The above uncertainty can be resolved by using the UL DAI IE value toindicate a same number of DL SAs transmitted in all cells regardless ofthe actual number of DL SAs transmitted in each cell. For example, inFIG. 13 or FIG. 15, the UL DAI IE indicates that there are 3 DL SAs inevery cell although the number of actual DL SAs in some cells, such ascell 1, is 2.

FIG. 16 illustrates the use of the UL DAI IE in a UL SA for a PUSCHwhere a UE multiplexes HARQ-ACK information to determine the HARQ-ACKpayload and ordering for the DL DAI design in FIG. 9 or in FIG. 10according to an exemplary embodiment of the present invention.

Referring to FIG. 16, based on the UL DAI value V_(DAI) ^(UL)=3, a UEgenerates HARQ-ACK bits assuming that the NodeB transmitted 3 DL SAs ineach DL cell. A predetermined ordering of cells is assumed, such as onebased on the Cell_Index. For the DL SAs it receives, the UE generates aHARQ-ACK corresponding to the outcome of the respective reception ofTBs, whether the outcome is correct or incorrect. In Cell 0 1610, the UEcan identify that it received 3 DL SAs and, as it is assumed to havebeen configured with a TM enabling the reception of 2 TBs, the UEgenerates 6 respective HARQ-ACK bits 1615. However, it should be notedthat if spatial bundling is used, 3 HARQ-ACK bits are generated.

In Cell 1 1620, the UE can identify that it received 1 DL SA and thatthe DL SA has a DL DAI IE value 1622 of 1. As the UL DAI IE indicates 3DL SAs 1640, the UE generates 2 additional HARQ-ACK bits placed afterthe first of the HARQ-ACK bits for a total of 3 HARQ-ACK bits 1625 (theUE is assumed to have been configured with a TM enabling the receptionof 1 TB in Cell 1). In Cell 2 1630, the UE can identify that it received1 DL SA and that it has a DL DAI IE value 1432 of 2. As the UL DAI IEindicates 3 DL SAs 1640, the UE generates 2 additional HARQ-ACK bitswith the first one placed before the HARQ-ACK bit corresponding to theTB reception in DL subframe 1 and the other placed after the HARQ-ACKbit corresponding to the TB reception for a total of 3 HARQ-ACK bits1635. It should be noted that the UE is assumed to have been configuredwith a TM enabling the reception of 1 TB in Cell 2. Therefore, theHARQ-ACK payload is as described in Equation (16),

O _(HARQ-ACK) =V _(DAI) ^(UL)·(C+C ₂)  Equation (16),

and the HARQ-ACK payload in the PUSCH is reduced from a maximum ofO_(HARQ-ACK)=N_(bundle)·(C+C₂)=16 bits in Equation (11) toO_(HARQ-ACK)=V_(DAI) ^(UL)·(C+C₂)=12 bits.

Alternatively, instead of indicating the maximum number of DL SAs percell, the UL DAI IE may indicate the total number of DL SAs over allcells. For example, this can be useful if spatial bundling is used sincethe configured TM in each cell does not affect the respective number ofHARQ-ACK bits. The mapping of the UL DAI IE value to the total number ofDL SAs can be configured for the UE by the NodeB. An example is shownbelow in Table 1. The UL DAI IE may also be extended to includeadditional bits in a case of DL CA in order to improve the granularityand accuracy of its indications. If a UE does not receive any DL SA, theUL DAI value of “11” is interpreted as 0.

TABLE 1 Mapping of UL DAI IE to total DL SAs a UE should assume in thebundling window. UL DAI Total DL SAs in bundling MSB, LSB V_(DAI) ^(UL)window N_(DAI) ^(UL) 0, 0 1 4 0, 1 2 8 1, 0 3 12 1, 1 0 or 4 0 or 16

In a case where multiple UL SAs are received for PUSCH transmission inrespectively multiple cells in the UL subframe associated with the DLsubframe bundling window, a UE may not consider the UL DAI IE in any ULSA as valid if it does not have the same value in all UL SAs. Also, ifbased on the DL DAI IE, the UE needs to generate more thanO_(HARQ-ACK)=V_(DAI) ^(UL)·(C+C₂) bits, it may either transmit theHARQ-ACK payload determined from the DL DAI IE in a PUSCH or the UE maynot transmit any PUSCH as, for proper system operation, this can beconsidered to represent an error case resulting from either the UEconsidering as valid an invalid DL SA or by considering as valid aninvalid UL SA.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention as defined by the appended claims and their equivalents.

What is claimed is:
 1. A method for a user equipment (UE) operating in atime division duplex (TDD) communication system to transmitacknowledgement information bits, the UE being configured by a basestation to have multiple downlink (DL) cells, the method comprising:determining size of acknowledgement information bits based on an uplink(UL) downlink assignment index (DAI) value of a received UL schedulingassignment (SA) for a physical uplink shared channel (PUSCH), if the ULSA for the PUSCH is received; generating the acknowledgement informationbits in response to at least one received data transport block (TB)within a bundling window in a cell c of the multiple DL cells; andtransmitting the acknowledgement information bits having the determinedsize via at least one of the PUSCH and a physical uplink control channel(PUCCH).
 2. The method of claim 1, further comprising: determining thesize of the acknowledgement information bits based on a number of DLsubframes in the bundling window in the cell c, if the UL SA for thePUSCH is not received.
 3. The method of claim 1, wherein the determinedsize of the acknowledgement information bits for the PUSCH is two timesa number corresponding to the DAI value if the cell c has a transmissionmode (TM) conveying a maximum of two data TBs, or the determined size ofthe acknowledgement information bits for the PUSCH is equal to thenumber corresponding to the DAI value if the cell c has a TM conveying amaximum of one data TB.
 4. The method of claim 2, wherein the determinedsize of the acknowledgement information bits for the PUSCH is two timesthe number of DL subframes in the bundling window if the cell c has atransmission mode (TM) conveying a maximum of two data TBs, or thedetermined size of the acknowledgement information bits for the PUSCH isequal to the number of DL subframes in the bundling window if the cell chas a TM conveying a maximum of one data TB.
 5. The method of claim 1,wherein the UL SA is received within the bundling window in the cell c.6. A user equipment (UE) apparatus operating in a time division duplex(TDD) communication system for transmitting acknowledgement informationbits, the UE being configured by a base station to have multipledownlink (DL) cells, the apparatus comprising: a controller configuredto determine size of acknowledgement information bits based on whetheran uplink (UL) downlink assignment index (DAI) value of a received ULscheduling assignment (SA) for a physical uplink shared channel (PUSCH)and to generate the acknowledgement information bits in response to atleast one received data transport block (TB) within a bundling window ina cell c of the multiple DL cells and, if the UL SA for the PUSCH isreceived; and a transceiver configured to transmit the acknowledgementinformation bits having the determined size via at least one of thePUSCH and a physical uplink control channel (PUCCH).
 7. The apparatus ofclaim 6, wherein the controller is further configured to determine thesize of the acknowledgement information bits based on a number of DLsubframes in the bundling window in the cell c, if the UL SA for thePUSCH is not received.
 8. The apparatus of claim 6, wherein thedetermined size of the acknowledgement information bits for the PUSCH istwo times a number corresponding to the DAI value if the cell c has atransmission mode (TM) conveying a maximum of two data TBs, or thedetermined size of the acknowledgement information bits for the PUSCH isequal to the number corresponding to the DAI value if the cell c has aTM conveying a maximum of one data TB.
 9. The apparatus of claim 7,wherein the determined size of the acknowledgement information bits forthe PUSCH is two times the number of DL subframes in the bundling windowif the cell c has a transmission mode (TM) conveying a maximum of twodata TBs, or the determined size of the acknowledgement information bitsfor the PUSCH is equal to the number of DL subframes in the bundlingwindow if the cell c has a TM conveying a maximum of one data TB. 10.The apparatus of claim 6, wherein the UL SA is received within thebundling window in the cell c.
 11. A method for a user equipment (UE)operating in a time division duplex (TDD) communication system todetermine size of acknowledgement information bits, the UE beingconfigured by a base station to have multiple downlink (DL) cells, themethod comprising: receiving at least one data transport block (TB)within a bundling window in a cell c of the multiple DL cells;determining size of acknowledgement information bits based on an uplink(UL) downlink assignment index (DAI) value of a received UL schedulingassignment (SA) for a physical uplink shared channel (PUSCH), if the ULSA for the PUSCH is received; generating the acknowledgement informationbits in response to the at least one received data TB; and transmittingthe acknowledgement information bits having the determined size via atleast one of the PUSCH and a physical uplink control channel (PUCCH).12. The method of claim 11, further comprising: determining the size ofthe acknowledgement information bits based on a number of DL subframesin the bundling window in the cell c, if the UL SA for the PUSCH is notreceived.
 13. The method of claim 11, wherein the determined size of theacknowledgement information bits for the PUSCH is two times a numbercorresponding to the DAI value if the cell c has a transmission mode(TM) conveying a maximum of two data TBs, or the determined size of theacknowledgement information bits for the PUSCH is equal to the numbercorresponding to the DAI value if the cell c has a TM conveying amaximum of one data TB.
 14. The method of claim 12, wherein thedetermined size of the acknowledgement information bits for the PUSCH istwo times the number of DL subframes in the bundling window if the cellc has a transmission mode (TM) conveying a maximum of two data TBs, orthe determined size of the acknowledgement information bits for thePUSCH is equal to the number of DL subframes in the bundling window ifthe cell c has a TM conveying a maximum of one data TB.
 15. The methodof claim 11, wherein the UL SA is received within the bundling window inthe cell c.
 16. A user equipment (UE) apparatus operating in a timedivision duplex (TDD) communication system for determining size ofacknowledgement information bits, the UE being configured by a basestation to have multiple downlink (DL) cells, the apparatus comprising:a controller configured to receive at least one data transport block(TB) within a bundling window in a cell c of the multiple DL cells, todetermine size of acknowledgement information bits based on an uplink(UL) downlink assignment index (DAI) value of a received UL schedulingassignment (SA) for a physical uplink shared channel (PUSCH), if the ULSA for the PUSCH is received, and to generate the acknowledgementinformation bits in response to the at least one data TB; and atransceiver configured to transmit the acknowledgement information bitshaving the determined size via at least one of the PUSCH and a physicaluplink control channel (PUCCH).
 17. The apparatus of claim 16, whereinthe controller is further configured to determine the size of theacknowledgement information bits based on a number of DL subframes inthe bundling window in the cell c, if the UL SA for the PUSCH is notreceived.
 18. The apparatus of claim 16, wherein the determined size ofthe acknowledgement information bits for the PUSCH is two times a numbercorresponding to the DAI value if the cell c has a transmission mode(TM) conveying a maximum of two data TBs, or the determined size of theacknowledgement information bits for the PUSCH is equal to the numbercorresponding to the DAI value if the cell c has a TM conveying amaximum of one data TB.
 19. The apparatus of claim 17, wherein thedetermined size of the acknowledgement information bits for the PUSCH istwo times the number of DL subframes in the bundling window if the cellc has a transmission mode (TM) conveying a maximum of two data TBs, orthe determined size of the acknowledgement information bits for thePUSCH is equal to the number of DL subframes in the bundling window ifthe cell c has a TM conveying a maximum of one data TB.
 20. Theapparatus of claim 16, wherein the UL SA is received within the bundlingwindow in the cell c.